Assembled type impeller of a cooling fan

ABSTRACT

An assembled type impeller includes a main impeller, and a secondary impeller; the main impeller has a hub, main blades on the hub, an extension portion next to one end of the hub, and a top portion over an upper end of the extension portion; the secondary impeller has a hub, secondary blades on the hub thereof, and a top portion over an upper end of the hub thereof; the secondary impeller is joined to the main impeller with the hub thereof being tightly fitted onto the extension portion, and with the secondary blades being connected to respective ones of the main blades to form larger blades; in manufacturing the main impeller, first a motor housing is positioned in a mold for the main impeller, and then the main impeller is made by means of injection molding; thus, the main impeller and the motor housing can be naturally connected together.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the invention

[0002] The present invention relates to an assembled type impeller of a cooling fan, more particularly one, whose main impeller is shaped such that a motor housing will be naturally and properly connected thereto as soon as the main impeller is formed by means of injection molding, and such that the manufacturing and assembling process is simpler, and balance of the impeller better.

[0003] 2. Brief Description of the Prior Art

[0004] Referring to FIGS. 5 and 6, in U.S. Pat. No. 6,318,964 B1, a “Complex Cooling Fan With Increased Cooling Capacity” is taught, which includes an upper impeller 4, and a lower impeller 5 joined to a lower end of the upper impeller 4; the upper impeller 4 has a hollow hub 41, and several upper curved blades 42 on an outer side of the hub 41; the lower impeller 5 has a hollow hub 51, and several lower curved blades 52 on an outer side of the hub 51. The impeller 4 is positioned on the impeller 5 with the lower end of the hub 41 being over an upper end of the hub 51, and with lower flat sides of the upper blades 42 being respectively over upper flat sides of the lower blades 52; thus, larger curved blades are formed, and there will be larger wind pressure, and cooling capacity when the cooling fan is working. And, the impellers 4, 5 are securely connected together by means of suitable methods, e.g. high frequency. Furthermore, the lower flat sides of the upper blades 42 are formed with fitting cavities 43, and the upper flat sides of the lower blades 52 are formed with fitting bumps 53, which are respectively fitted in the fitting cavities 43. A motor housing 6 is tightly fitted in the hubs 41, 51 after the impellers 4, 5 are connected together.

[0005] Referring to FIGS. 5 and 6, in U.S. patent application publication No. 2003/0118449 A1, a “Cooling Fan With Curved V-shaped Impellers” is taught, whose structure is basically the same as that of the above one, and which is different from the above one only in the shape of blades.

[0006] Both of the above cooling fans are found to have disadvantages as followings:

[0007] 1. Because the lower impeller has a hollow hub with two open ends, it is difficult to prepare an injection port for the lower impeller, and the lower impeller will change shape more easily.

[0008] 2. The motor housing has to be fitted in the hubs after the lower and the upper impellers are connected together therefore the manufacturing process is complicated, and it is difficult to fit the motor housing into the hubs properly.

SUMMARY OF THE INVENTION

[0009] It is a main object of the present invention to provide an assembled type impeller of a cooling fan to overcome the above disadvantages.

[0010] The assembled type impeller includes a main impeller, and a secondary impeller. The main impeller has a hub, several main blades on an outer side of the hub, an extension portion next to one end of the hub, and a top portion formed over an upper end of the extension portion. The secondary impeller has a hub, several secondary blades on an outer side of the hub thereof, and a top portion formed over an upper end of the hub thereof. The secondary impeller is joined to the main impeller with the hub thereof being closely fitted onto the extension portion of the main impeller, and with the secondary blades being connected to respective ones of the main blades to form larger blades. In manufacturing the main impeller, first a motor housing is positioned in a mold for the main impeller, and then the main impeller is made by means of injection molding; thus, the main impeller and the motor housing can be naturally and properly connected together, and there won't be disadvantage of the motor housing being fitted in the hub after the main impeller has been made. Because of the top portion of the main impeller, the hub of the main impeller is closed at the upper end, and can't change shape when it is subjected to higher temperature. Consequently, the impeller has better balance after it is assembled.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be better understood by referring to the accompanying drawings, wherein:

[0012]FIG. 1 is an exploded perspective view of the assembled type impeller according to the present invention,

[0013]FIG. 2 is a cross-sectional view of the assembled type impeller according to the present invention,

[0014]FIG. 3 is an exploded perspective view of the complex cooling fan as taught in U.S. patent No. 6,318,964 B1,

[0015]FIG. 4 is a cross-sectional view of the complex cooling fan as taught in U.S. patent No. 6,318,964 B1, and

[0016]FIG. 5 is an exploded perspective view of the cooling fan as taught in U.S. patent application publication No. 2003/0118449 A1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Referring to FIGS. 1 and 2, a preferred embodiment of an assembled type impeller of a cooling fan in the present invention includes a main impeller 1, and a secondary impeller 2, both of which are made by means of injection molding. The main impeller 1 has a hub 11, several main curved blades 12 on an outer side of the hub 11, an extension portion 111 next to an upper end of the hub 11, and a top portion 14, which has a flat upper side, over an upper end of the extension portion 111; thus, the extension portion 111 and the top portion 14 together form a cylinder with a closed upper end, and have a vertical section with a “

”-shape. The extension portion 111 has an outer diameter smaller than an outer diameter of the hub 11.

[0018] The secondary impeller 2 has a hub 21, secondary curved blades 22 on an outer side of the hub 21 thereof, and a flat top portion 24 over an upper end of the hub 21; thus, the hub 21 and the top portion 24 together form a cylinder with a closed upper end, and have a vertical section with a “

”-shape.

[0019] Furthermore, an injection port used for making the main impeller 1 is located on the center of the top portion 14 such that the top portion 14 will be uniformly shaped, and can't change shape easily owing to significant change of temperature.

[0020] The main and the secondary impellers 1 and 2 are connected together with the hub 21 being tightly fitted onto the extension portion 111 of the main impeller 1, and with the secondary blades 22 being joined to respective ones of upper sides of the main blades 12 at lower sides thereof such that the whole impeller has larger curved blades after assembly. In addition, the main blades 12 are formed with fitting bumps 13 on the upper sides thereof while the secondary blades 22 are formed with fitting cavities 23 on the lower sides thereof for holding the fitting bumps 13 therein.

[0021] In manufacturing, first a motor housing 3 is positioned in a mold for the main impeller 1, and then the main impeller 1 is made by means of injection molding such that the main impeller 1 and the motor housing 3 will be naturally and properly connected together as soon as the main impeller 1 is formed. Next, the secondary impeller 2 is fitted onto the extension portion 111 of the main impeller 1 at the hub 21 thereof with the fitting bumps 13 being fitted in the fitting cavities 23, and with the flat top portion 24 being closely pressed against the upper side of the top portion 14. Finally, the impeller 1 and 2 are securely joined to each other by means of suitable methods, e.g. high frequency.

[0022] From the above description, it can be easily understood that when being compared with those of the prior arts, the assembled type impeller of the present invention has advantages as followings:

[0023] 1. The injection port used for injection in molding the main impeller 1 is located on the center of the top portion 14, therefore the top portion 14 is easy to form in injection molding, and can't change shape easily owing to significant change of temperature.

[0024] 2. Before forming the main impeller 1 by means of injection molding, the motor housing 3 is positioned in the mold for the main impeller 1, therefore the main impeller 1 and the motor housing 3 will be naturally and properly connected together, and the manufacturing process simpler, and more efficient.

[0025] 3. Because the main impeller 1 and the motor housing 3 are naturally connected together when the main impeller 1 is formed, there won't be disadvantage of the motor housing being fitted into the hubs, and the whole impeller has higher precision, and better balance. 

What is claimed is:
 1. An assembled type impeller of a cooling fan, comprising a main impeller having a hub, and a plurality of main blades on an outer side of the hub; the main impeller having a “

”-shaped extension portion next to one end of the hub thereof; and a secondary impeller having a hub, and a plurality of secondary blades on an outer side of the hub thereof; the secondary impeller being joined to the main impeller with the hub thereof being closely fitted onto the extension portion of the main impeller, and with the secondary blades being connected to respective ones of the main blades to form larger blades.
 2. The assembled type impeller of a cooling fan as claimed in claim 1, wherein the extension portion is next to an upper end of the hub of the main impeller, and the main impeller is further formed with a top portion over the “

”-shaped extension portion thereof, and the secondary impeller is further formed with a top portion over an upper end of the hub thereof for the hub to have a “

”-shape; the top portion of the secondary impeller being closely pressed against the top portion of the main impeller after the impellers are connected together. 